There are apparently companies out there that specialize in low volume semi-custom enclosures. They are a lot like the cheap PCB manufacturers that we are now blessed with in their economies of scale. I think the guy mentioned the price for this power supply enclosure was around $35 (BTW, it's a really nifty power supply. There is a long thread on EEVBLOG covering its development. It uses and Arduino Due for the processor.)
https://www.crowdsupply.com/envox/eez-h24005